1. Field of the Disclosure
The present disclosure relates to a multi-flow optical transceiver constituting a wavelength division multiplex (WDM) network and a multi-flow optical transponder and multi-flow optical node using the same. More specifically, the present disclosure relates to a multi-flow optical transceiver which can set a plurality of variable paths through which an optical signal is transmitted in addition to having a function of varying a wavelength, a bit rate, a modulation method, and a signal bandwidth, and a multi-flow optical transponder and multi-flow optical node using the same.
2. Discussion of the Background Art
An optical communication network realizes various functions such as a reconfigurable optical add/drop multiplexer (ROADM) and wavelength cross connect by using a wavelength division multiplex (WDM) technique. Moreover, a colorless function in which an add/drop port does not depend on a wavelength and a directionless function capable of transmitting a signal to all paths without changing the add/drop port can be realized by using a wavelength-tunable transceiver and a wavelength selective switch (WSS). Since the wavelength-tunable transceiver can significantly reduce the variety in comparison with a fixed wavelength transceiver, in addition to an operational advantage that the number of kinds to be managed can be reduced, the wavelength-tunable transceiver has succeeded in significantly reducing the cost by volume efficiency. Regarding WSS, introduction of WSS is advanced in order to increase the number of paths of an ROADM node. Wavelengths of the wavelength-tunable transceiver and a pass center wavelength of WSS are arranged on a grid specified in ITU-T and at constant intervals of 50 GHz, for example.
Meanwhile, in order to more efficiently contain optical signals having different bit rates or optical signals having different transmission distances from the view point of spectral efficiency, there has been proposed an elastic optical path network in which the optical modulation method and the center frequency intervals of adjacent optical signals are adaptively adjusted according to required conditions of individual signals. In the elastic optical path network, the function of varying the bit rate, the modulation method, and the signal bandwidth are important as well as the wavelength-tunable function of the optical transceiver (for example, see Non-Patent Literatures 1 and 2).